This invention relates to photographic elements, couplers and processes including novel 1H-pyrazolo[1,5-b][1,2,4]triazole-based couplers having a ring carbon bearing a propionic ester moiety.
Color images are customarily obtained in the photographic art by reaction between an oxidation product of a silver halide developing agent and a dye-forming coupler. Pyrazolones are useful for forming magenta dye images; however, such couplers have shortcomings with respect to color reproduction in that the unwanted absorption around 430 nm causes color turbidity. Bicyclic pyrazolo couplers, particularly pyrazolotriazole couplers, represent another class of couplers for this purpose. Examples of pyrazoloazole couplers are described in, for example, U.S. Pat. Nos. 4,443,536, 4,665,015; 4,514,490; 4,621,046, 4,540,654; 4,590,153; 4,822,730 and European Patents 177,765 and 119,860. One class of pyrazolotriazole couplers includes 1H-pyrazolo[3,2-c][1,2,4]triazole couplers and another includes 1H-pyrazolo[1,5-b][1,2,4]triazole couplers, such as described in European Patent 177,765. While these couplers have a reduced level of unwanted absorption, the spectral absorption is often deeper having absorption maxima at higher wavelengths than is desired. Frequently addenda must be added to bring the hue into a usable range.
It is a problem to be solved to provide 1H-pyrazolo[1,5-b][1,2,4]triazole couplers that exhibit desirable hue characteristics.
The present invention provides a photographic element comprising a light sensitive silver halide emulsion layer and, having associated with that layer a 1H-pyrazo[1,5-b]-1,2,4-triazole dye forming coupler having a fully substituted carbon atom at the 6-position, a chloro group at the 7-position, and, at the 2-position, a propionic ester moiety.
It has been found that photographic elements containing these couplers exhibit desirable hue characteristics.